In a computer, there are some points where a data transmission is performed using a plurality of signal lines between semiconductor devices such as an LSI etc.
FIG. 1 is an explanatory view illustrating the data transmission between conventional semiconductor devices.
A semiconductor device 800 transmits data to a semiconductor device 900 through a transmission unit. The transmission unit is provided with a plurality of buses (signal lines), and data is transmitted from the semiconductor device 800 to the semiconductor device 900 using the plurality of buses.
The semiconductor device 900 confirms using the received data whether or not a transmission error has occurred in the data. If the semiconductor device 900 confirms an occurrence of a transmission error, it requests the semiconductor device 800 to retransmit the data, and ignores (discards) subsequent requests (packets). In response to the retransmission request from the semiconductor device 900, the semiconductor device 800 retransmits the data to the semiconductor device 900 through a transmission unit.
FIG. 2 is a flowchart illustrating the flow of the process of realizing a data transmission between conventional semiconductor devices. FIG. 2 illustrates the processes performed in the transmitting semiconductor device (“transmitting LSI” in FIG. 2) and the receiving semiconductor device (“receiving LSI” in FIG. 2).
The transmitting device executes the data transmission control (ST51), adds a check code in the CRC system to the data to be transmitted (ST52), and transfers the data (ST53).
On the other side, the receiving device receives the transferred data (SR51), performs an error check by the CRC (SR52), and notifies the transmitting device of the check result as a reception result (SR53).
Upon receipt of the reception result notification, the transmitting device decodes the notified reception result, and determines whether or not a transmission error has occurred (ST54). If a transmission error has occurred in the receiving device (YES in ST54), the data having a transmission error is selected during control of the data transmission (ST51). If no transmission error has occurred (NO in ST54), the data to be next transmitted is selected in the data transmission control (ST51).
Thus, the conventional semiconductor device simply requests a retransmission of data when a transmission error has occurred in the received data.
Recently, the data transmission speed of a computer has been greatly enhanced between semiconductor devices such as LSIs etc. A high-speed data transmission greatly serves in realizing higher data processing capacity. However, a higher data transmission speed causes errors more frequently in the data transmission through a bus. The occurrences of the errors interfere with high-speed data processing. Thus, it is considered that obtaining more pieces of information to counter errors occurring during the data transmission through a bus is very important hereafter.
Reference documents can be Japanese Published Patent Application No. 2003-188858 and Japanese Published Patent Application No. 2000-349742.